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Harman [31]
2 years ago
13

Of the 800 seventh grade students and 640 eighth grade students at ​Knox Middle School, 90 students will be chosen at random to

attend an ​assembly.
​
​Which of the following would be a representative sample of ​the number of seventh and eighth grade students at the school?
Mathematics
1 answer:
Irina18 [472]2 years ago
3 0

Answer:

50 7th grade and 40 8th grade

Step-by-step explanation:

1. add to get total number of students, 1440

2. find percentage of total that are 7th grade students and 8th grade student:

640/1440 = ~45% (are 7th grade)

800/1440 = ~55% (are 8th grade)

3. 55% of 90 is 50, and 45% of 90 is 40

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Westkost [7]

Answer:

dy/dx = -b/a cot α

Step-by-step explanation:

x² / a² + y² / b² = 1

Take derivative with respect to x.

2x / a² + 2y / b² dy/dx = 0

2y / b² dy/dx = -2x / a²

dy/dx = -b²x / (a²y)

Substitute:

dy/dx = -b²a cos α / (a²b sin α)

dy/dx = -b cos α / (a sin α)

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